A gas turbine engine typically includes a fan section, a compressor section, a combustor section, and a turbine section. A fan section may drive air along a bypass flowpath while a compressor section may drive air along a core flowpath. In general, during operation, air is pressurized in the compressor section and is mixed with fuel and burned in the combustor section to generate hot combustion gases. The hot combustion gases flow through the turbine section, which extracts energy from the hot combustion gases to power the compressor section and other gas turbine engine loads. The compressor section typically includes low pressure and high pressure compressors, and the turbine section includes low pressure and high pressure turbines.
The fan section, compressor section, and turbine section typically include a series of rotor systems. Rotor systems typically include a disk and a plurality of circumferentially spaced blades. Hollow blades may advantageously reduce the weight associated with the larger blades. To increase a strength of the hollow blade, a series of ribs may extend between opposing interior surfaces of the blade. At various operating frequencies the blades may experience increased vibration and/or blade flutter due to the natural resonant modes of the blade structure. Increased vibration and/or blade flutter may lead to increased blade fatigue and/or increased noise.